Abstract The replication of EV1, a British isolate of maedi visna virus (MVV), in macrophages has not previously been studied. We therefore used transmission and scanning electron microscopy (TEM and SEM respectively) to compare the replication of EV1 in macrophages versus skin cell lines. Monocyte-derived macrophages (MDM), alveolar macrophages (AM) and skin cell lines were all permissive for replication by EV1. Virus grew rapidly and to high titers in skin cell lines and mature MDM. However replication was slower in less mature MDM or AM. Virion budding occurred through (i) cytoplasmic membranes only (skin cells), (ii) cytoplasmic and vesicular membranes (MDM) or (iii) vesicular membranes only (AM). This meant that virions accumulated in vacuoles within macrophages. Retroviral intracytoplasmic type A particles were seen in the cytoplasm of AM and MDM infected with strain EV1, but not MDM infected with strain 1514 (an Icelandic MVV strain) and were shown to contain MVV gag antigen by immunogold staining.