This paper deals with the estimation of unequally
spaced panel data regression models with AR(1) remainder
disturbances. A feasible generalized least squares (GLS)
procedure is proposed as a weighted least squares that
can handle a wide range of unequally spaced panel data
patterns. This procedure is simple to compute and provides
natural estimates of the serial correlation and variance
components parameters. The paper also provides a locally
best invariant test for zero first-order serial correlation
against positive or negative serial correlation in case
of unequally spaced panel data.