Document and Entity Information	Mar. 19, 2020
Prospectus:
Document Type	497
Document Period End Date	Mar. 19, 2020
Registrant Name	DREYFUS CASH MANAGEMENT
Entity Central Index Key	0000759667
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Mar. 19, 2020
Document Effective Date	Mar. 19, 2020
Prospectus Date	May 31, 2019
Dreyfus Cash Management \| Institutional Shares \| DREYFUS CASH MANAGEMENT
Prospectus:
Trading Symbol	DICXX
Dreyfus Cash Management \| Investor Shares \| DREYFUS CASH MANAGEMENT
Prospectus:
Trading Symbol	DVCXX
Dreyfus Cash Management \| administrative shares \| DREYFUS CASH MANAGEMENT
Prospectus:
Trading Symbol	DACXX
Dreyfus Government Cash Management \| dreyfus government cash management - Investor Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DGVXX
Dreyfus Government Cash Management \| dreyfus government cash mangement - Institutional Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DGCXX
Dreyfus Government Cash Management \| dreyfus government cash management - Administrative Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DAGXX
Dreyfus Government Cash Management \| Dreyfus Government Cash Management - Participant Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DPGXX
Dreyfus Government Securities Cash Management \| Dreyfus Government Securities Cash Management - Investor Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DVPXX
Dreyfus Government Securities Cash Management \| Dreyfus Government Securities Cash Management - Institutional Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DIPXX
Dreyfus Government Securities Cash Management \| Dreyfus Government Securities Cash Management - Administrative Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DAPXX
Dreyfus Government Securities Cash Management \| Dreyfus Government Securities Cash Management - Participant Shares \| DREYFUS GOVERNMENT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DGPXX
Dreyfus AMT-Free Municipal Cash Management Plus \| Institutional Shares \| DREYFUS AMT-FREE MUNICIPAL CASH MANAGEMENT PLUS
Prospectus:
Trading Symbol	DIMXX
Dreyfus AMT-Free Municipal Cash Management Plus \| Investor Shares \| DREYFUS AMT-FREE MUNICIPAL CASH MANAGEMENT PLUS
Prospectus:
Trading Symbol	DVMXX
Dreyfus AMT-Free Municipal Cash Management Plus \| Participant Shares \| DREYFUS AMT-FREE MUNICIPAL CASH MANAGEMENT PLUS
Prospectus:
Trading Symbol	DMUXX
Dreyfus AMT-Free New York Municipal Cash Management \| Participant Shares \| DREYFUS AMT-FREE NEW YORK MUNICIPAL CASH MANAGEMENT
Prospectus:
Trading Symbol	DMDXX
Dreyfus AMT-Free New York Municipal Cash Management \| Investor Shares \| DREYFUS AMT-FREE NEW YORK MUNICIPAL CASH MANAGEMENT
Prospectus:
Trading Symbol	DVYXX
Dreyfus AMT-Free New York Municipal Cash Management \| Institutional Shares \| DREYFUS AMT-FREE NEW YORK MUNICIPAL CASH MANAGEMENT
Prospectus:
Trading Symbol	DIYXX
Dreyfus AMT-Free Tax Exempt Cash Management Fund \| DREYFUS AMT-Free TAX EXEMPT CASH MANAGEMENT - Institutional Shares \| DREYFUS TAX EXEMPT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DEIXX
Dreyfus AMT-Free Tax Exempt Cash Management Fund \| DREYFUS AMT-FREE TAX EXEMPT CASH MANAGEMENT - Investor Shares \| DREYFUS TAX EXEMPT CASH MANAGEMENT FUNDS
Prospectus:
Trading Symbol	DEVXX
Dreyfus Treasury Obligations Cash Management \| Participant Shares \| Dreyfus Treasury Obligations Cash Management
Prospectus:
Trading Symbol	DTPXX
Dreyfus Treasury Obligations Cash Management \| Administrative Shares \| Dreyfus Treasury Obligations Cash Management
Prospectus:
Trading Symbol	DTAXX
Dreyfus Treasury Obligations Cash Management \| Investor Shares \| Dreyfus Treasury Obligations Cash Management
Prospectus:
Trading Symbol	DTVXX
Dreyfus Treasury Obligations Cash Management \| Institutional Shares \| Dreyfus Treasury Obligations Cash Management
Prospectus:
Trading Symbol	DTRXX
Dreyfus Treasury Securities Cash Management \| Institutional Shares \| DREYFUS TREASURY SECURITIES CASH MANAGEMENT
Prospectus:
Trading Symbol	DIRXX
Dreyfus Treasury Securities Cash Management \| Investor Shares \| DREYFUS TREASURY SECURITIES CASH MANAGEMENT
Prospectus:
Trading Symbol	DVRXX
Dreyfus Treasury Securities Cash Management \| Administrative Shares \| DREYFUS TREASURY SECURITIES CASH MANAGEMENT
Prospectus:
Trading Symbol	DARXX
Dreyfus Treasury Securities Cash Management \| Participant Shares \| DREYFUS TREASURY SECURITIES CASH MANAGEMENT
Prospectus:
Trading Symbol	DPRXX

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