  We implement inflation within a realistic supersymmetric SO(10) model in
which the doublet-triplet splitting is realized through the Dimopoulos-Wilczek
mechanism, the MSSM $\mu$ problem is resolved, and higgsino mediated dimension
five nucleon decay is heavily suppressed. The cosmologically unwanted
topological defects are inflated away, and from $\delta T/ T$, the $B-L$
breaking scale is estimated to be of order $10^{16}-10^{17}$ GeV. Including
supergravity corrections, the scalar spectral index $n_s = 0.99\pm 0.01$, with
$|dn_s/ d{\rm ln}k| \lapproxeq 10^{-3}$.
