Abstract
We present images of the neutral hydrogen (H I) in the direction of the compact group of galaxies HCG 18. This H I emission is identified with a single cloud, centered on the galaxies b, c, and d and smoothly distributed over a region twice the size of the compact group. The cloud appears to be in regular rotation with a period no longer than 8 X 10^8^ yr. The systematic velocity of the gas lies within 1σ of the mean velocity of the group; however, the cloud is not clearly associated with any particular galaxy, but surrounds all three, which may be one irregular galaxy.
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