Relic Gravitational Waves and Limits on Inflation

It is shown that only a narrow class of inflationary models can possibly agree with the available observational data on the anisotropy of the cosmic microwave background radiation (CMBR). These models may be governed by ``matter’’ with the effective equation of state $-1.2<p\mathrm{/}ϵ<-0.6$ which includes the De-Sitter case $p\mathrm{/}ϵ=-1$.