The low-loss and uniform dielectric properties of sapphire make it attractive for high-performance microwave devices using high-temperature superconductors. YBa2Cu3O7-delta films have been deposited on oxide-buffered 5-cm-diameter wafers and demonstrated a surface resistance of 0.5 mOMEGA at 10 GHz and 77 K. Long (9-ns) delay lines have for the first time been produced on these substrates and have a measured insertion loss of 1.5 dB at 6 GHz and 77 K. Design techniques appropriate for the dielectric anisotropy of sapphire are discussed.