Five stratigraphically linked polarity intervals (R1→R5 and N1→N5) from Late Arenig to Early Caradoc (Ordovician) times are recognized within the Gullh¿gen Limestone section, southern Sweden. The reversal frequency should be considered as a minimum given extremely low sedimentation rates (1--3 m/m.y.). Primary magnetite, probably detrital or biogenic in origin, is the prevailing remanence carrier in addition to early diagenetic hematite. A conspicuous reversal asymmetry, in which the remanence directions of the two lowermost normal polarity sections (N1 and N2) depart significantly from otherwise nearly antiparallel and typical Lower Ordovician directions, has been identified. This reversal asymmetry is mainly in declination. An artifact of remagnetization cannot be entirely ruled out, but we find this explanation rather unsatisfactory given the lack of systematic magneto-mineralogical or isotope variations (Δ18O and Δ13C) within these anomalous normal polarity horizons. The anomalous strata involved do not exhibit a different degree or extent of diagenetic alteration or magnetomineralogical character when compared to horizons above and below carrying the reverse polarity directions. We therefore suggest nonzonal nondipole field disturbances, lasting some 1--1.5 m.y. as a likely source, in order to explain these normal polarity anomalies. If the observations appear to be global, the results question the fundamental palaeomagnetic concept of symmetric reversals throughout geological time. ¿ American Geophysical Union 1995